Excitation-contraction coupling is a series of events that occur after the events of the neuromuscular junction have transpired. The term excitation refers to which step in the process?

Excitation refers to the shape change that occurs in voltage-sensitive proteins in the sarcolemma.
Excitation refers to the release of calcium ions from the sarcoplasmic reticulum.
Excitation, in this case, refers to the propagation of action potentials along the sarcolemma.
Excitation refers to the propagation of action potentials along the axon of a motor neuron.

What means of membrane transport is used to release the neurotransmitter into the synaptic cleft?

a protein carrier
exocytosis
a channel

The binding of the neurotransmitter to receptors on the motor end plate causes which of the following to occur?

Binding causes voltage-gated sodium channels to open in the motor endplate.
Binding causes chemically gated potassium channels to open in the motor end plate.
Binding causes potassium voltage-gated channels to open in the motor endplate.
Binding of the neurotransmitter causes chemically gated sodium channels to open in the motor end plate.

The action potential on the muscle cell leads to contraction due to the release of calcium ions. Where are calcium ions stored in the muscle cell?

What is the role of calcium in the cross bridge cycle?

Calcium binds to troponin, exposing the active site on troponin.
Calcium binds to myosin, causing the myosin head to release from the actin myofilament.
Calcium binds to active sites on actin, forming the cross bridge.
Calcium binds to troponin, altering its shape.

Where in the cross bridge cycle does ATP hydrolysis occur?

during the power stroke
during the cocking of the myosin head
during the removal of calcium from troponin
during the movement of tropomyosin to expose the active sites on actin

How/when does the myosin head cock back to store energy for the next cycle?

The power stroke cocks the myosin head.
The sliding of the actin myofilament during the power stroke re-cocks myosin heads that have previously delivered their power stroke.
After the myosin head detaches, energy from ATP hydrolysis is used to re-cock the myosin head.
when ADP is released from the myosin head

BMD (2,3-butanedione 2-monoximime) inhibits myosin, such that ATP can bind to myosin but myosin is unable to hydrolyze the bound ATP. What effect would BMD have on the cross bridge cycle?

Tropomyosin would not move, and the active sites on actin would not be exposed.
Myosin heads would remain detached, unable to cock.
Myosin heads would remain attached to actin, unable to perform the power stroke.
Myosin heads would remain attached to actin, unable to detach.

During contraction, what prevents actin myofilaments from sliding backward when a myosin head releases?

The actin myofilament can only move in one direction relative to the myosin filament.
The cross bridge remains in place, preventing the actin myofilament from sliding.
Calcium blocks the active sites on actin.
There are always some myosin heads attached to the actin myofilament when other myosin heads are detaching.